IOS SWIFT 타이머 설정하기 (NSTimer)

import UIKit
 
class ViewController: UIViewController {
    
    var timer:NSTimer?
    var count = 0
    
    override func viewDidLoad() {
        super.viewDidLoad()
        self.startTimer()
        // Do any additional setup after loading the view, typically from a nib.
    }
 
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
 
    func startTimer(){
        self.timer = NSTimer.scheduledTimerWithTimeInterval(0.1, target: self, selector: "update", userInfo: nil, repeats: true)
    }
    
    func update(){
        //0.5초마다 반복
        print("update")
        
        count++
        if(count > 10){
            self.stopTimer()
        }
    }
    
    func stopTimer(){
        self.timer?.invalidate()
        self.timer = nil
    }
 
}